E46Fanatics - View Single Post - water pump diy
Thread: water pump diy
View Single Post
Old 10-02-2012, 07:26 PM   #9
Registered User
Join Date: Nov 2010
Location: Minnesota
Posts: 59
My Ride: 99 328i
Originally Posted by Oz Striker View Post
Hi all i have a specific query relating to if you are only just replacing the water pump. I've never done any DIYs before that involved any sort of refilling & bleeding of coolant system, but I've done all my reading up on it and feel pretty confident, so shouldn't have any issues there.

However I dont want remove my splash guard/ undertray as I've only just got it fitted securely with cable ties last week whilst the car was on ramps (dont ask, essentially cause i have M3 rep bumper). So approx how much coolant is going to spill out when i remove the water pump if i dont drain any coolant from the radiator drain plug? Is it going to be a few litres or are we talking just a small loss? Either way I'll be topping up and bleeding, but just would like to know ho much i'll be expecting and how much coolant to have handy.
I would say darn near a gallon. If you just want to refill, you don't have to worry about flushing the system. However I would flush the system if your water pump already went and it was a plastic impellor. When my WP went I had to use almost a whole gallon mix. When you do it, make sure you are going to go ahead and replace the belts or pull them both because coolant on them will cause slippage and wear out quicker. Also be sure to clean the out of the pullys. As far as bleeding goes. Do not start your car but put it in the run position with the heat on max and the fan on low. Open the top of your expansion tank and remove the bleeder screw...the large plastic screw right by your filler cap. Then keep adding until the bleeder screw over flows and the level does not drop down. BINGO DONE.

Read my posting:

I just did mine yesturday + the Thermostat (you might as well since your right there). Here is my posing about it with a couple of links:


The biggest issue is torquing down the bolts. I snapped of the threaded studs for the water pump. Lucky me, I was able to extract it and I just used a bolt of similar length. Also, make sure you check your expansion tank for cracks as I understand it tends to go when the WP does. And if your WP is plastic, get all the pieces if it shattered. Lastly make sure you get the factory replacment as it has a metal impellor. Most that are sold at auto parts store as still plastic and many of the metal after market ones are stamped sheet metal. In my posting you can see the difference between the factory replacment and the cheap aftermarket metal one.

If you have any questions feel free to ask. This is a very easy job and if it wernt for a few minor hiccups, I would have been done it a few hour.

Good luck.
kowalzekc is offline   Reply With Quote